This invention relates to a method of producing a magnetic head slider equipped with a magnetic resistance element of the type of the giant magnetic resistance effect or the tunnel magnetic resistance effect, and to the magnetic head slider. More particularly, the invention relates to a method of forming a film for protecting an air bearing surface featuring excellent corrosion resistance and wear resistance.
Modern magnetic disk recording/reproducing devices are rapidly increasing their recording densities to cope with an increase in the amount of information to be processed accompanied, however, by an unavoidable technical problem for decreasing the magnetic spacing which is a distance between the magnetic head and the magnetic disk. However, a decrease in the flying amount of the magnetic head results in increased chances of contact or collision of a magnetic head slider with a magnetic disk surface that is revolving at a high speed. Therefore, the air bearing surface overcoat formed on the air bearing surface of the magnetic head slider must have a high wear resistance in addition to being thin and tough. On the other hand, a magnetic head element constituting the magnetic head slider includes a magnetic recording element and a magnetic resistance element which are both made of a magnetic material that is liable to be corroded. Therefore, the air bearing surface overcoat must also play the role of preventing the corrosion of the magnetic material. To meet these requirements, it has been desired to provide a thin film which does not permit dust and dirt to be left when sliding, which features excellent wear resistance, which has a high atomic density and is highly dense, and which further remains chemically stable. At present, there has been used a film stack of an amorphous carbon film and an amorphous silicon film as an air bearing surface overcoat since it satisfies the above requirements to some extent. The carbon film in the air bearing surface overcoat is formed relying upon a chemical vapor deposition (CVD) method, an ion beam evaporation method, a laser abrasion evaporation method or a filtered cathodic vacuum arc (FCVA) method. The amorphous carbon film is constituted by a diamond component and a graphite component. Here, the amorphous carbon film formed by using the above method contains the diamond component in a relatively large amount and, hence, exhibits excellent corrosion resistance and wear resistance.
There has been known that an attempt for further decreasing the thickness of the air bearing surface overcoat encounters the following problems. That is, the air bearing surface of the slider must be mechanically polished (lapped) prior to forming an air bearing surface overcoat on the air bearing surface of the slider. In the mechanical polishing, the height of the magnetic element is controlled by press-sliding the air bearing surface of the slider on a grinding machine in which the diamond grains are buried. However, the air bearing surface of the slider is constituted by several kinds of materials, that is, a substrate, an insulating film, a magnetic head element, a protection film and the like having different mechanical strengths leaving a problem of forming steps among the portions constituted by these materials after the mechanical polishing. When the steps are great near the magnetic head element on the air bearing surface of the slider, the coating performance of the air bearing surface overcoat formed after the mechanical polishing is deteriorated making it difficult to produce a magnetic head having a satisfactory corrosion resistance.
There has been reported in a non-patent document 1 (H. U. Jager et al., “ta-C deposition simulations: Film properties and time-resolved dynamics of film formation” (Physical Review B 68, 2003, pp. 024201)) that the hard amorphous carbon film formed by the CVD method, ion beam evaporation method, laser abrasion evaporation method or FCVA method contains a lesser diamond component and has a lower atomic density (hereinafter called surface graphite layer) in a region of a depth of from about 0.5 nm to about 1.5 nm from the film surface than those in the deeper regions. When the thickness of the air bearing surface overcoat is smaller than 3.0 nm, the surface graphite layer occupies an increased proportion of the whole film causing, as a result, a decrease in the corrosion resistance.
A patent document 1 (JP-A-2000-90423) discloses a technology for solving part of the above problem. Namely, the patent document 1 discloses a method of producing a magnetic head slider comprising a step of forming a hard amorphous carbon film on the air bearing surface of the magnetic head slider, and a step of forming a protection film by removing the surface region having low wear resistance from the hard amorphous carbon film by mechanical polishing or by the irradiation with a gas plasma. According to this method of producing the magnetic head slider, there can be provided a magnetic head formed with a very thin air bearing surface overcoat having excellent wear resistance by utilizing a dense inner region only.